Coffee Leaf Rust: A New Reality For Specialty Coffee

RustGiuliano2By Jesse Bladyka

In the specialty coffee industry, we have heard a lot over the last few years about Coffee Rust (Roya in Spanish), also known as Hemileia vastatrix. This fungus has been affecting coffee crops in devastating ways since the late 19th century. While it can be managed through the use of hybrid cultivars, our beloved Coffea arabica is very sensitive to its effects. For a long time, the saving grace for specialty coffee was the fungus’s cold sensitivity. This means that the highest-grown coffees were located in areas outside of the range of the fungus, and generally safe. However, things are changing, and in the last few years Coffee Rust has devastated even the highest regions of Central America. Many farms have lost their entire production; many others have been unable to produce the quality of coffee their buyers require.

Two years ago at Symposium, we heard about rust in extraordinary detail from leading plant pathologist, Mary Catherine Aime. She enlightened us about how rust is a primitive fungus, and perhaps because it evolved so long ago, some of the other plants involved in its life cycle during evolution may have become scarce, or even gone extinct.

Bladyka Leaf RustThis year we heard more about Coffee Rust from Harry Evans, principal scientific officer of CABI, whose work focuses on “[improving] people’s lives by providing information and applying scientific expertise to solve problems in agriculture and the environment.” Evans studies classical biological control (CBC), which means identifying co-evolved naturally occurring enemies to control pests and pathogens, rather than using intensive chemical application or aggressive management techniques. Evans noted that as we see the effects of climate change, rust becomes more prevalent in specialty coffee growing regions. Through his study of possible “natural enemies” of coffee rust, he has realized an important point. Coffee rust may not have evolved with Coffea arabica, but may have evolved with Coffea canephora (robusta). This is an important realization because it has led him to look in different regions for co-evolved species.

11130199_10153142740852789_8197623329453832760_nWe also heard an important perspective from Michael Sheridan of Catholic Relief Services. He spoke about the conflict between Caturra, a traditional arabica cultivar, and Castillo, a hybrid cultivar developed by Colombia to provide disease resistance. Throughout his talk, he urged coffee buyers to consider the premium that they pay for traditional cultivars—not only a quality premium, but also a risk premium. Producers who choose to continue growing rust-susceptible cultivars do so at an enormous risk. He shared a pilot study in which there was very little difference perceived between the two varieties by coffee tasters from all types of companies. This is encouraging news for Castillo, and for the small producers in Colombia, but many buyers are still asking for traditional cultivars.

Coffee Rust is a new reality for specialty coffee. Producers who thought they were not susceptible three years ago have lost their entire farms to the fungus. There are fungicide- and plant-health-based management approaches, and many farmers are replacing their trees with hybrids, but not all are fortunate to have the cup quality of Castillo. This is why we all need to support World Coffee Research, an organization conceived of at the first Symposium, which is working hard to combat coffee rust and other dangers to coffee through plant breeding. Recently, they met with plant breeders from all over the world in Guatemala to discuss a strategy for their project. You can read more about this in The Specialty Coffee Chronicle that will be available this weekend at the Event.

Jesse Bladyka is a coffee roaster, Roasters Guild member, and SCAA credentialed instructor.